Method of laser welding the housing of a rechargable battery

ABSTRACT

A rechargeable battery including a housing formed from two components formed from polyphenysulfone plastic. One housing component has a lip that is located inwardly of the other housing component. The housing components are further formed so that photonic energy at a select wavelength passes through the outer component and is absorbed by the lip of the second component. Once a rechargeable cell is placed in in one of the housing components, the housing components are placed together so the lip of the second component abuts an inner surface of the first component. Photonic energy at the select wavelength is directed to the joint between the components. The photonic energy passes through the first component and heats the lip of the second component. The heat causes the lip to melt. The melting plastic forms a hermetic weld between the housing components.

RELATIONSHIP TO EARLIER FILED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.14/031,380 now U.S. Pat. No. ______. U.S. patent application Ser. No.14/031,380 is a divisional of U.S. patent application Ser. No.12/582,740 filed 21 Oct. 2009, now U.S. Pat. No. 8,564,242. U.S. patentapplication Ser. No. 12/582,740, is a divisional of U.S. patentapplication Ser. No. 11/551,335 filed 20 Oct. 2006, now abandoned. U.S.patent application Ser. No. 11/551,335 claims priority under 35 U.S.C.Sec 119 from U.S. Provisional Patent App. No. 60/729,338 filed 21 Oct.2005. The contents of the priority applications are incorporated hereinby reference.

FIELD OF THE INVENTION

This invention is related to a system and method for recharging abattery. More particularly, this invention is related to a system andmethod for both charging a battery and evaluating the state of health ofthe battery. This invention is further related to a system and methodfor obtaining data from the power consuming devices to which a batteryis connected.

BACKGROUND OF THE INVENTION

A battery often energizes a powered surgical tool used in an operatingroom to perform a surgical procedure. The use of a battery eliminatesthe need to provide a power cord connected to an external power source.The elimination of the power cord offers several benefits over cordedsurgical tools. Surgical personnel using this type of tool do not haveto concern themselves with either sterilizing a cord so that it can bebrought into the sterile surgical field surrounding the patient orensuring that, during surgery, an unsterilized cord is not inadvertentlyintroduced into the surgical field. Moreover, the elimination of thecord results in the like elimination of the physical clutter andfield-of-view blockage the cord otherwise brings to a surgicalprocedure.

In an operating room, batteries are used to power more than the toolsused to perform the surgical procedure. Batteries are also used toenergize the power consuming components integral with a personalprotection system surgical personnel sometimes wear when performing aprocedure. This system typically includes some type of hooded garment.Internal to the garment is a ventilation unit for circulating air withinthe garment. Some of these systems also have lights for illuminating thesurgical site or radios that facilitate conventional spoken levelconversation with other persons involved in performing the procedure.Each of these units, the ventilation unit, the light unit and the radio,requires a source of power. By providing this power from the battery,the need to attach cords to each individual wearing such a unit iseliminated. This, in turn, reduces number of cords in the operating roompersons would otherwise have to avoid. Further, eliminating these cordslikewise eliminates the restrictions of movement they place on theindividual using the system.

An integral part of any battery-powered device is, naturally, thebattery. Most battery-powered surgical devices used in an operating roomare designed to be used with rechargeable batteries. These rechargeablebatteries typically include one or more NiCd cells. Once a battery isdischarged, it is coupled to a complementary charger. The chargerapplies a current to the battery's cells to store energy in the cells.

Unlike other rechargeable batteries, a rechargeable battery intended foruse with a surgical tool must be sterilizable so that it can be placedin close proximity to the open surgical site on a patient. Often, thesebatteries are sterilized by placing them in an autoclave wherein theatmosphere is saturated with water vapor (steam), the temperature isapproximately 270° F. (132° C.) and the atmospheric pressure isapproximately 30 psi (Gage) (1552 mmHg). The repetitive exposure to thisenvironment causes a battery cells' ability to store electric charge todegrade. Often this is referred to as degradation in the “state ofhealth” of the battery.

The Applicant's U.S. Pat. No. 6,018,227, BATTERY CHARGER ESPECIALLYUSEFUL WITH STERILIZABLE RECHARGEABLE BATTERY PACKS, issued Jan. 25,2000 and incorporated herein by reference, discloses a means todetermine the voltage at load of a battery. Inferentially, this is ameasure of the internal resistance of the battery. Unfortunately, thisinformation alone does not provide a complete measure of the batterystate of health. For example, this information alone does not provideinformation if the stored energy is sufficient to power the device towhich the battery is attached for the time required to perform thesurgical procedure. This means that, during the performance of aprocedure, if the battery's stored energy appreciably depletes, theprocedure is interrupted to replace the battery. This increases theoverall time takes to perform the procedure. This interruption runscontrary to one of the goals of modern surgery which is to perform theprocedure as quickly as possible so as to lessen the time the patient'sinternal organs are exposed, and therefore open to infection, and theamount of time a patient is held under anesthesia.

Moreover, there is an interest in having surgical equipment provide dataregarding their own operating states to other equipment in the hospital.For example, some motorized surgical tools are provided with internaltemperature sensors. In the event a bearing assembly internal to a toolof this type malfunctions, tool temperature will start to rise. Thisrise in temperature is detected by the complementary sensor. The outputsignal from the sensor can then be read by a remote device in thehospital. This gives hospital personnel notice that the tool may beapproaching a critical malfunction and should be repaired or replaced.

Corded surgical devices provide these types of operating state data.These communications systems are relatively simple technically andeconomical to provide because the signals are forwarded to thecomplementary control consoles through the cords through which power issupplied to these devices. One can also provide the data from thesedevices through wireless communications systems. One system is disclosedin the Applicant's U.S. Patent Application No. 60/694,592, POWEREDSURGICAL TOOL WITH SEALED CONTROL MODULE, filed 28 Jun. 2005, thecontents of which are published in U.S. Pat. No. 7,638,958 B2,incorporated herein by reference. A disadvantage of the above-mentionedsystem is that it requires the addition of a wireless communicationssystem into the operating room. The expense of providing such a systemlimits the locations where they are installed.

The Applicant's Assignee's U.S. Pat. No. 5,977,746, RECHARGEABLE BATTERYPACK AND METHOD FOR MANUFACTURING SAME, issued 2 Nov. 1999 andincorporated herein by reference, discloses a rechargeable batteryespecially designed to withstand the rigors of autoclave sterilization.The battery of this invention includes a cluster of cells that are boundtogether by top and bottom plastic binders. Conductive straps extendingbetween openings formed in the binders connect the cells. One of thestraps is a fuse that opens upon a more than a specific current flowingthrough it. More specifically, the current through the fuse heats thematerial forming the fuse so a section of the fuse vaporizes. Thisvaporization of the fuse section separates the rest of the fuse into twosections.

The above battery pack has proven useful for storing the charge neededto energize a cordless surgical tool. However, the cells internal to thebattery pack can generate significant amounts of heat. This causes thetemperature of the cells to rise. Sometimes, the temperature risebetween the cells is uneven. This uneven thermal loading of cells canresult in an electrical imbalance of the cells. If the cells become soimbalanced, both the immediate utility of the battery to supply energyat a particular time and its useful lifetime may diminish.

SUMMARY OF THE INVENTION

This invention relates to a new and useful battery and battery chargingsystem. The battery is designed for use in a harsh environment such asin a hospital where the battery is autoclave sterilized. The battery andbattery charging system of this invention are further designed to recordand transmit data about the devices the battery is used to energize.

The battery of this invention includes a set of rechargeable cells. Alsointernal to the battery are a data recording unit and a temperaturesensor. Both the data recording unit and temperature sensor are poweredby the battery cells so that they are always on, regardless of whetheror not the battery is being used to power a device or is being charged.Collectively, the data recording unit and temperature sensor areconfigured to record data about the temperature of the battery.

The battery charger of this invention includes a current source forcharging the battery. Also internal to the battery charger is aprocessor and a load resistor. The processor regulates the actuation ofthe current source and connection of the battery to the load resistor.

The processor also reads the data stored in the battery data recordingunit. Depending on the data indicating the history of the battery, theprocessor may conduct a state of health evaluation of the battery. Forexample, a state of health evaluation may be performed if the data inthe data recording unit indicates that battery was continually at atemperature above a threshold level for more than a given period oftime. To perform a state of health evaluation, the processor bothmeasures the voltage-at-load of the battery and the quantity of energyinput to the battery. Often, this last evaluation is made by first fullydischarging the battery. The results of the state of health evaluationare displayed.

Another feature of this invention is that, while the battery is beingused to power a device, the device writes data into the data recordingunit. When the battery is attached to the charger, the data recordingunit writes out the stored device data to the charger processor. Thecharger processor, in turn, forwards these data to another device. Thus,information about the operating state of a battery powered device isavailable to persons charged with maintaining the device. Thisinformation is available even though there is no corded link orRF/IR/ultrasonic wireless communications link to the device.

The battery of this invention is also configured to foster uniformdissipation of the heat generated by the cells internal to the pack.This minimizes the temperature imbalance of the cells. The minimizationof the temperature imbalance reduces the electric imbalance between thecells. The reduction of this electrical imbalance results in a likereduction in the extent to which the cells, if electrically imbalanced,adversely affect battery performance. The battery of this invention isfurther constructed to have a fuse that will regularly open when adefined amount of current flows through the fuse. The battery of thisinvention is also economical to manufacture and occupies a relativelysmall surface area.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is pointed out with particularity the in the claims. Theabove and further features and benefits of the battery, battery chargerand method for charging a battery of this invention may be betterunderstood from the following detailed description taken in conjunctionwith the accompanying drawings in which:

FIG. 1 is a perspective view of a battery and battery charger of thisinvention;

FIG. 2 is a perspective view of the battery;

FIG. 3 is an exploded view of the battery of this invention;

FIG. 4 is a perspective view of the battery housing;

FIG. 5 is a cross sectional view of the battery housing;

FIG. 5A is an enlarged cross sectional view of the top edge of thebattery housing;

FIG. 6 is an exploded view of the cell cluster internal to the battery;

FIG. 7 is an exploded view of the binder assembly, here the top binderassembly, of the cell cluster;

FIG. 8 is a plan view of the thermal fuse internal to the top binderassembly;

FIG. 9 is a cross sectional view of the battery lid;

FIG. 10 is a plan view of the undersurface of the battery lid;

FIG. 11 is an enlarged cross sectional view of the bottom lip of thebattery lid;

FIG. 12 is a schematic drawing of the electrical components internal tothe battery;

FIG. 13 is a block diagram of some of the sub circuits internal to thebattery microcontroller;

FIG. 14 depicts some to types of data stored in the memory integral withthe battery microcontroller;

FIG. 15A is a plan view illustrating one of the fixtures in which thecomponents forming the cell cluster are placed in order to facilitateassembly of the cluster;

FIG. 15B is side view illustrating how the components forming the cellcluster are fitted in a pair of fixtures;

FIG. 16 is a diagrammatic illustration of the welding process used tocomplete the assembly of the cell cluster

FIG. 17 is a cross sectional view of the interface of the batteryhousing and battery lid prior to the welding of these componentstogether;

FIG. 18 is diagrammatic representation of how the battery housing andlid are welded together;

FIG. 19 is a cross sectional view of the interface of the batteryhousing and battery lid after the welding process;

FIG. 20 is an exploded view of relationship of the charger base to thecharger housing;

FIG. 20A is a perspective view of how the discharger resistors andcomplementary heat sink are secured to the charger base;

FIG. 21 is a cross sectional view of some of the components internal tothe charger;

FIG. 22 is a block diagram of sub-circuits internal to the charger and amodule attached to the charger;

FIGS. 23A and 23B collectively form a flow chart of the process stepsperformed by the battery microcontroller to monitor the autoclaving ofthe battery;

FIGS. 24A, 24B and 24C collectively form a flow chart of the processsteps executed by the charger in order to charge a batter according tothe process of this invention;

FIG. 25 is a flow chart of the process steps executed by the processorinternal the charger to ensure that the charger temperature does notrise to potentially unsafe levels;

FIG. 26 is a block diagram illustrating of the tool communicationssystem of this wherein the battery and charger are used to facilitatethe exchange of data between the surgical tool and other components;

FIG. 27 is a block diagram of the components of tool of the system ofthis invention;

FIG. 28 is a block diagram of data stored in the tool history fileinternal to the battery microcontroller; and

FIG. 29 is a flow diagram of the process steps executed in the toolcommunication system of this invention.

DETAILED DESCRIPTION I. Overview

FIG. 1 illustrates a battery 40 and battery charger 42 constructed inaccordance with this invention. Battery 40, includes a set ofrechargeable cells 44 (FIG. 3) a microcontroller 46 and a temperaturesensor 48 (FIG. 12). Battery charger 42 includes a housing 50 with anumber of pockets 52 (FIG. 20). Each pocket 52 removably receives amodule 54 associated with a specific type of battery. The module 54 isshaped to define a complementary socket 56 for receiving the head end ofthe associated battery 40. Internal to the battery charger 42 arecomponents for reading the data stored in the battery microcontroller 46and for charging the battery cells 44. A plurality of I/O units 58 areattached to the charger 42. Each I/O unit 58 functions as thesub-assembly through which instructions are entered and charge stateinformation presented about an individual one of the batteries 40attached to the charger 42.

II. Battery and Method of Battery Assembly

As seen in FIGS. 2 and 3, a battery 40 of this invention includes ahousing 60. Rechargeable cells 44 are arranged in a cluster 62 seatingin housing 60. A lid 66 is sealing disposed over the open top end of thehousing 60. Lid 66 is formed with a head 68. The lid 66 is the batterystructural component to which the microcontroller 46 and temperaturesensor 48 are mounted. In the illustrated version of the invention, thelid head 68 is dimensioned to fit into a complementary socket formed inthe power tool 522 (FIG. 22) the battery 40 is intended to power. Thelid head 68 is provided with two contacts 70 and a single contact 72.Contacts 70 are the conductive members through which the charger 42applies a charging current to the cells 44 and from which the power tool522 (FIG. 23) draws an energizing current. Contact 72 is the contactthrough which data and instructions are written into and read out fromthe microcontroller 46. Thus, data are exchanged between the charger 42and battery microcontroller 46 using a one-wire signal exchangeprotocol. One such protocol is the Dallas Semiconductor One-Wireprotocol.

Battery housing 60 is formed from a single piece of plastic that istransmissive to light energy emitted at 980 nanometers. By“transmissive” it is understood the plastic is at least “partially”transmissive. In most versions of the invention the plastic is at least55% percent transmissive. In more preferred versions, the plastic is atleast 75% transmissive. In one version of the invention, housing 60 isformed from a polyphenylsulfone plastic. One such plastic from whichhousing 60 is formed is sold under the brand name RADEL by SolvayAdvanced Polymers, of Alpharetta, Ga., United States. This plastic ispartially transparent. For aesthetic reasons, the plastic forminghousing 60 may be dyed to be opaque at visible wavelengths. If housing60 is so dyed, the dye should be selected so that it does notappreciably interfere with transmissivity of photonic energy at the 980nanometer range. As discussed below this is the wavelength at which, inone process lid 66 is laser welded to housing 60.

As seen in FIGS. 4, 5 and 5A, housing 60 is formed to have a generallyrectangular base 76. Four interconnected walls 78 extend upwardly fromthe perimeter edges of the base 76. For aesthetic reasons, the cornersof the base 76 and the corners where walls 78 abut are rounded. Housing60 is further shaped so that walls 78 taper outwardly away from base 76.The housing 60 is further formed so that ribs 80 extend inwardly fromthe inner surfaces of the walls 78 from the top surface of the base 76.Each wall 78 may be formed with one, two or more ribs 80. Ribs 80provide structural rigidity to the walls and minimize movement of thecell cluster 62 within the housing 60.

Each housing wall 78 has an inner vertical surface 86. (In the crosssectional view of FIG. 5 rib 50 is seen below the top of the innersurface 86.) Above the inner vertical surface 86 there is a tapered face88 that angled outwardly relative to the vertical surface 86. A reveal90 forms the top most portion of each lip 78. The reveal 90 has agenerally square cross sectional profile. The width of the reveal 90 isless than that of the vertical surface 91 that extends between the topedge of the lip outer surface 85 and the top edge of tapered inner face88. Housing 60 is thus formed so that reveal 90 is located inwardly ofboth the top edge of the lip outer surface and the top edge of thetapered inner face 88.

As seen by reference to FIG. 6, the cell cluster 62 includes a pluralityof rechargeable cells 44. As is known from the above-identified,incorporated herein by reference U.S. Pat. No. 5,977,746, the outercylindrical surface of each cell 44, which functions as the cell ground,is covered with polyimide tape, (not shown).

Cells 44 are arranged in a three abutting rows 92, 94 and 96, such thatthe cells in one row abut the cells in the adjacent row. In each row92-94, the adjacent cells 44 abut. The cells 44 are arranged so thatthere are three cells in the outer rows, rows 92 and 96, and two cellsin the center row, row 94. This arrangement ensures that each cell hasan outer perimeter section of at least 10% and, more preferably at least20%, that neither abuts an adjacent cell nor is concealed behind anadjacent row of cells. Thus a perimeter section of at least 10%, andmore preferably at least 20%, of each cell 44 forms a portion of theouter perimeter of the array of cells forming the cell cluster 62.

The top and bottom orientation, the orientations of, respectively, thepositive and negative terminals, of the cells 44 is arranged as afunction to the extent the cells are to be connected together in aseries or parallel arrangement in order to provide a charge at aparticular voltage level and current.

The cells 44 are held together to form the cluster 62 by top and bottombinder assemblies 102 and 104, respectively. Each binder assembly 102and 104 includes a number of conductive straps 106 that are in the formof thin strips of metal. As seen in FIG. 7, which shows the top binderassembly 102, each binder assembly includes inner and outer binders 108and 110, respectively. (For reference, the “inner” binder is understoodto be the binder closest to the cells 44; the “outer” binder is spacedfrom the cells.) Each binder 108 and 110 is formed from a flexibleplastic material such as a polyester sold under the trademark MYLAR byDuPont. Each binder 108 and 110 is formed with a number of openings 112and 114, respectively. Binders 108 and 110 forming the upper binderassembly 102 are further formed so as to define along the outerperimeter thereof aligned notches 116 and 117, respectively.

Conductive straps 106 are sandwiched between the binders 108 and 110.Each conductive strap 106 is positioned to have one end that extendsinto the space subtended by aligned pair of binder openings 112 and 114.Some conductive straps 106 are positioned so that that the second endsof the straps extend into one of the aligned pairs of binder openings112 and 114. These conductive straps 106 electrically connect theterminals of adjacent cells 44. Two of the conductive straps 106 arepositioned so that their second ends project beyond the perimeters ofthe binders 108 and 110. These two conductive straps 106, seen in FIG.6, function as the members that provide electrical connections betweenthe cell cluster 62 and the contacts 70.

A fuse 118 is also disposed between the binders 108 and 110 forming topbinder assembly 102. The fuse 118, best seen in FIG. 8, is formed of aconductive metal that when the current flow therethrough causes materialheating to the point the metal vaporizes. In one version of theinvention, fuse 118 is formed from nickel or a nickel alloy. Fuse 118 isgenerally in the form of a planar strip. The fuse 118 is further formedso as have notch 120 that extends inwardly from the one of thelongitudinal side edges of the metal strip forming the fuse. (Thegeometries of notch 120 of the fuse of FIG. 7 and of the fuse 118 ofFIG. 8 are slightly different.) In FIG. 8, section 119 of fuse 118, thenarrowest width section, defines the widest portion of notch 120.

A binder assembly 102 or 104 of this invention is assembled by firstplacing one of the binders 108 and 110 in a jig. More particularly, thejig is formed with a recess designed in which the binders 108 and 110are designed to precisely seat. Extending into the recess from the baseof the jig are spaced apart fingers. The fingers extend through into thespaces subtended by binder openings 112 and 114. The fingers are spacedso as to define spaces therebetween into which the conductive straps 106and fuse 118 are seated.

The exposed surface of the binder 108 or 110 seated in the jig recess isprovided with an adhesive. In some versions of the invention, theadhesive is pre-applied to the binder 108 or 110. At manufacture, aprotective sheet that covers the adhesive is removed. In FIG. 7, theadhesive is represented as stippling 124 on inner binder 108.

Once the first binder 108 or 110 is set in the jig, the conductivestraps 106 and fuse 118 are set over the binder. More specifically, theconductive straps 106 and fuse 118 are set between the fingers thatextend through the binder openings 112 or 114. The second binder 110 or108 is then disposed over the partially assembled unit. In some versionsof the invention, adhesive material may also disposed over the surfaceof the second binder that abuts the first binder.

As a consequence of the assembly of the binders 108 and 110, each innerbinder opening 112 is aligned with an associated one of the upper binderopenings 114. Inner and outer binder notches 116 and 117, respectively,are also aligned. It should further be appreciated that, during theassembly of the binder assembly 102, fuse 118 is positioned so that fusenotch 120 is within the area where the binders 108 and 110 aresandwiched together. The portion of the fuse 118 that defines fuse notch120 is within the space subtended by binder notches 116 and 117. In morepreferred versions of the invention, the fuse is positioned so that thethinnest section of the fuse, the portion defining the widest section offuse notch 120, is spaced from the binders 108 and 110.

The battery lid 66 is now described by reference to FIGS. 2, 9, and 10.In one version of the invention, lid 66 is a single component formedfrom a polyphenelsulfone plastic such as the RADEL R plastic. Foraesthetic reasons, the plastic forming the lid may be dyed to be opaqueat the visible wavelengths. If the lid 66 is to be secured to thehousing 60 by the below discussed laser welding process, the lid shouldbe formed of material that absorbs the photonic energy at the wavelengthemitted by the laser. The aesthetic dye can function as this material.Thus, in the described version of the invention, the dye absorbs energyemitted in the 980 nanometer range. Lid 66 is shaped to have a generallyrectangular base 126 that has a geometry that subtends the top edges ofthe housing walls 78. Four panels 128, 130, 132 and 134 extend inwardlyand upwardly from the sides of the base 126. The panels 128-134 meet ata planar horizontal surface 136 from which the battery head 68 upwardlyprojects. Panels 128 and 132 are the side panels and are symmetricrelative to each other. Panel 130 is the front panel; panel 134 is therear panel. Relative to the horizontal plane, front panel 130 has asteep upward slope; the slope of rear panel 134 is shallower.

Battery head 68 is formed to have a slot 136 and two slots 138. Each ofslots 136 and 138 are open to the front face of the head 68. Slot 136 iscentered along the longitudinal centerline of the battery 40. Slots 138are parallel to and located on either side of slot 138. Contact 72, thecontact through which signals are exchanged with microcontroller 46extends into slot 136. Contacts 70, the contacts through which charge isstored in and drawn from cells 44, is disposed in slots 138.

A latch 140 is pivotally mounted to the battery head. The latch 140holds the battery 40 to the power consuming device to which the batteryis connected. A pressure relief valve 142 is mounted to horizontalsurface under the latch 140. Not identified are the openings in whichlatch 140 and valve 142 are mounted and the assembly that pivotallyholds the latch to the battery lid 66.

A number of ribs 146 and 148 extend inwardly from the inner surface oflid panels 128-134. The ribs 146 and 148 are generally rectangular inshape and extend into the inner surface of the lid below horizontalsurface 135. Ribs 146 are relatively tall; ribs 148 are short. Two ribs146 extend inwardly from panels 128, 132 and 134. A single rib 148extends inwardly from front panel 130. An additional rib 148 extendsinwardly from each of the side panels 128 and 132 immediately adjacentthe front panel. Each rib 148 is further formed so that the outer end isdownwardly stepped relative to the portion of the rib immediatelyadjacent the panel from which the rib extends. Ribs 146 and 148minimize, if not completely block, vertical displacement of the cellcluster 62.

Battery lid 66 also has a lip 152 that extends downwardly from the base126 around the perimeter of the lid. As seen best in FIG. 11, the lip152 is located inwardly of the outer vertical surface of the base 126.Lid 66 is formed so that lip 152 has an inner vertical surface 154 thatis flush with the adjacent inner surface of the base 126. The lip 152has an outer vertical surface 156 located inward of the outer perimeterof the base 126. The lip 152 is further formed to have a tapered surface158 that extends below vertical surface 154. Surface 158 tapers inwardtoward the center of the lid 66. A rectangularly shaped flange 160 formsthe bottommost portion of lip 152 and, by extension, the bottommoststructural feature of the battery lid 66. The bottommost portion ofinner vertical surface 154 forms the inner surface of flange 160. Aparallel vertical surface 164 that is inwardly stepped relative to theadjacent surface 158 forms the outer wall of the flange 160.

Battery lid 66 is further formed to define a rectangular notch 166 thatextends upwardly from the bottom surface of base 126. The base 126 isformed so that notch 166 is located immediately in front of and ispartially defined by lip outer vertical surface 156. In some versions ofthe invention, the notch is absent from the lid 66.

Returning to FIG. 3, it can be seen that a printed circuit board 170 ismounted in the battery lid 66. Printed circuit board 170 is thecomponent to which battery microcontroller 46 and temperature sensor 48are mounted (not illustrated). Circuit board 170 is fitted in the lid 66to seat against the inwardly stepped edges of ribs 148. A post 172extends upwardly from the printed circuit board 170. A screw 174 thatextends through lid horizontal surface 135 into post 172 holds thecircuit board 170 to the lid.

Seen extending from circuit board 170 are two conductors 176. Conductors176 provide an electrical connection between the cells 44 and thecomponents on the circuit board 170. As discussed in more detail below,energization signals are continually applied to microcontroller 46 andtemperature sensor 48 of battery 40 regardless of whether or not thebattery is being charged, discharged, autoclaved, or simply in storage.

Also seen in FIG. 3 are the wire assemblies 177 that extend from thecell cluster to contacts 70. Also seen in the Figure but not otherwisedescribed further are the button head fasteners 178 and lock washers 179that hold the contacts 70 and 72 in position. Also seen is the O-ring180 disposed around post 172.

FIG. 12 is a schematic of the electrical circuit components integralwith the battery 40. A voltage regulator 182 is connected to thepositive output terminal of the cell cluster 62. In one version of theinvention voltage regulator produces a 3.3 VDC signal, the signalpresent at point 183. A capacitor 184, tied between the pin of thevoltage converter 182 at which the 3.3 VDC signal is present and ground,filters the 3.3 VDC signal.

One of the components to which the 3.3 VDC signal is applied is themicrocontroller 46. One suitable unit that can be used asmicrocontroller 46 is the P89LPC925 8 bit microcontroller manufacturedby Philips Electronics N.V. of the Netherlands. Microcontroller 46 has anumber of different sub-circuits, a number of which are now described byreference to FIG. 13. A central processing unit (CPU) 185 controls mostof the operation of microcontroller 46 and the components connected tothe microcontroller. A non volatile flash memory 187 stores instructionsexecuted by the CPU 185. As discussed below, memory 187 also stores: theinstructions used to regulate the charging of the battery; datadescribing the use history of the battery; and data describing the usehistory of the tool 522 to which the battery is attached.

A random access memory 188 functions as a temporary buffer for data readand generated by microcontroller 46. A CPU clock 189 supplies the clocksignal used to regulate the operation of the CPU 185. While shown assingle block for purposes of simplicity, it should be appreciated thatCPU clock 189 includes an on-chip oscillator as well as sub-circuitsthat convert the output signal from the oscillator into a CPU clocksignal. A real time clock 190 generates a clock signal at fixedintervals as discussed below.

The output signal from the temperature sensor is applied to both ananalog comparator 191 and an analog to digital converter 192. In FIG. 13the above sub-circuits are shown interconnected by a single bus 193. Itshould be appreciated that this is for simplicity. In practice,dedicated lines may connect certain of the sub circuits together.Likewise it should be understood microcontroller 46 may have othersub-circuits. These sub-circuits are not specifically relevant to thisinvention and so are not described in detailed.

FIG. 14 illustrates types of data stored in the flash memory 187 inaddition to the instructions executed by the microcontroller 46. Thesedata include, in a field or file 194, data that identifies the battery.These data, in addition to serial number, lot number and manufactureridentification can include data such as an authorization code. This codeis read by the tool 522 or charger 42 to which the battery is connectedto determine if, respectively the battery can power the tool or berecharged by the charger. The battery identification data may includedata indicating the useful life of the battery. Useful life data areunderstood to be one or more of the following data types: batteryexpiration data; number of chargings; and number of autoclavings. Otherdata in identification file 194 can indicate the nominal open circuitvoltage of the signal produced by the battery, the current the batterycan produce and the joules of available energy.

Charging instructions for the battery are stored in a file 195. Thesedata can be the types of data described in the memories of the batteriesdisclosed in incorporated by reference U.S. Pat. Nos. 6,018,227, and6,184,655. Flash memory 187 also contains data describing the chargingand autoclave histories of the battery. In a field 196 data are storedindicating the number of times the battery was charged. A measuredpost-charge voltages file 197 contains data indicating the measuredvoltages-at-load of the battery after each charging. In some versions ofthe invention file 197 only contains these measurements for the last 1to 10 chargings. In a file 198 data are stored indicating the highestbattery temperature measured during its previous chargings. Again, file198 may only contain data indicating the highest temperatures measuredduring the last 1 to 10 chargings of the battery.

A field 199 stores data indicating the total number of times the batteryhas been autoclaved. A cumulative autoclave time field 200, as its nameimplies, is used to store data indicating the total time the battery hasbeen at temperatures at or above a threshold considered to be theautoclave temperature.

A field 201 contains data indicating the number of times the battery hasbeen exposed to potentially excessive autoclavings. Data indicating thecumulative time the battery may have been potentially excessivelyautoclaved is stored in a field 202. A peak autoclave temperature field203 contains data indicating the highest autoclave temperature to whichhas been exposed. A file 204 contains records of the time the batteryhas been in the autoclave for each of its autoclavings. In some versionsof the invention, time in autoclave file 204 only contains dataindicating the time the battery was in the autoclave for each of itslast 5 to 100 autoclavings. A file 205 contains data indicating the peaktemperatures of the battery that measured during its last 5 to 100autoclavings. In most versions of the invention, memory 187 storesautoclave time and temperature data for the exact same number ofautoclavings. Field 206 contains data indicating the period of thelongest single time the battery was subjected to autoclaving.

Memory 187 also contains a tool history file 229. As discussed below,tool history file 229 stores data obtained from the tool 522 thatbattery 40 is employed to power.

Returning to FIG. 12, other circuit components internal to battery 40are now described. Temperature sensor 48 is any suitable temperaturesensing device capable of detecting whether or not battery 40 is exposedto autoclave temperatures. In the described versions of the invention,temperature sensor 48 is a thermistor. The 3.3 VDC is applied to one endof the temperature sensor. The opposed end of the temperature sensor 48is tied to ground through a resistor 207. A capacitor 208 is tied acrossresistor 207. The voltage present at the junction of the temperaturesensor 48 and resistor 207 is applied as the T SENSE signalrepresentative of detected temperature to the noninverting input ofmicrocontroller comparator 191 (connection not specifically shown.)

A reference voltage, V_(TEMP) _(—) _(REF), is applied to the invertinginput of comparator 191 (connection not specifically shown.) Thereference voltage is the signal present at the junction of seriesconnected resistors 209 and 210. The opposed end of resistor 209receives a reference voltage from a source internal to microcontroller46. The opposed end of resistor 210 is selectively tied to groundthrough a switch internal to the microcontroller 46 (switch notillustrated).

Microcontroller 48 is connected to battery contact 72 by a conductor211. A pair of series-connected opposed diodes 212 extend betweenconductor 211 and ground.

As part of the process of assembling battery 40, cell cluster 62 isassembled. Initially, binder assemblies 102 and 104 are fabricated asdescribed above. Then, a first binder assembly 102 or 104 is placed in afixture 213 a or 213 b, FIG. 15A illustrating fixture 213 a, the fixturein which the top binder assembly 102 is seated. Each Fixture 213 a and213 b includes a base plate 214 formed with a number of openings 215. Ablock 216 extends upwardly from the fixture base plate. Block 216 isshaped to define a recess 223 dimensioned to slip fit receive the binderassembly 102 or 104 and cells 44. The block 216 is formed to define thepattern of the rows 92, 94 and 96 in which the cells are to be placed.Illustrated fixture 213 a is further shaped to define two opposed slots224 that are contiguous with recess 223. Slots 224 receive the free endof the top binder assembly conductive straps 106 that function aselectrical connections. Thus, fixture 213 a has a supplemental block 216a spaced from block 216 so as to define slots 224 therebetween.

Fixture openings 215 are formed in the fixture base plate 214 to beconcentric with the binder openings 112 and 114. When a cell is fittedin the fixture 213 a or 213 b it should be appreciated the cell iscentered with binder openings 112 and 114 and the associated fixtureopening 215.

The second binder assembly 104 or 102 is then placed in its associatedfixture 213 b or 213 a, respectively. As seen in FIG. 15B, the secondfixture with fitted binder assembly is then fitted over the fixtureassembly in which the binder assembly 102 or 104 and cells 44 arealready placed.

A robotic welding unit 218, shown diagrammatically in FIG. 16, welds theconductive straps 106 and fuse 118 to the cells 44. Specifically,robotic welding unit 218 has a base 237 to which an arm 232 is attached.Arm 232 includes two opposed fingers 233 that, when brought together,clamp cells 44 and fixtures 213 a and 213 b therebetweeen. A drivemechanism, (not illustrated,) moves arm 232 and the components heldthereby both in the X plane (to the left and right in FIG. 16) and inthe Y-plane (in and out of the plane of FIG. 16).

Robotic welding unit 218 also includes a welding head 230. Head 230 isattached to a track 234 so as to be able to move in Z-plane, (verticallyin FIG. 16). Two opposed electrodes 235 and 236 are attached to andextending downwardly from head 230.

The welding process begins with the placement of thesandwiched-between-fixtures cells 44 and binders 102 and 104 betweenfingers 233 of arm 232. Arm 232 is moved so that a first one of thefixture openings 215 is disposed below electrodes 235 and 236. Weldinghead 230 is lowered so that the electrodes 235 and 236 pass through thefixture opening 215 and the aligned binder opening 114 to the surface ofthe exposed conductive strap 106 (or fuse 118). Current is flowedbetween the electrodes 235 and 236 to weld the strap 106 (or fuse 118)to the surface of the underlying cell 44. Once this weld process iscomplete, head 230 is raised. Arm 232 is slightly repositioned so thatwhen head 230 is again lowered, electrode 235 and 260 can make a secondweld joint between the same strap 106 (or fuse 118) and cell 44.

After the two weld joints for the first strap (or fuse) cell interfaceare completed, head 230 is again raised. Arm 232 is again positioned soeach strap- (or fuse-) and-cell interface is similarly welded.

The final assembly of the battery 40 begins with the seating of a shockabsorber 217 seen in FIG. 3, in the base of the housing 60. The shockabsorber 217 is formed from a compressible material such as a siliconrubber. Shock absorber 217 subtends the area subtended by the cellcluster 62. In some versions of the invention, the shock absorber 217is, in an earlier step bonded to the exposed face of the bottom binderassembly 104. Cell cluster 62 is placed in the housing. The connectionsare made between the cell cluster 62 and conductors 176 and wireassemblies 177.

Lid 66 is then welded to the housing 60 to complete the assembly of thebattery 40. In this process, the lid 66 is seated on the housing so thatlid tapered surface 158 abuts housing tapered face 88. As seen in FIG.17, owing to the dimensioning of housing 60 and lid 66, at this time,the lid is positioned so that the bottom horizontal surface of the lidbase 126 is spaced above the housing reveal 90.

The welding process is accomplished by applying a downward force on thelid 66 so that the lid bears against the housing 60. In FIG. 18, this isrepresented diagrammatically by arrow 225. More particularly, owing tothe angled profile of housing tapered surface 88 and lid tapered surface158, these surfaces 88 and 158 abut. Simultaneously with application ofthe downward force, coherent (laser) light at 980 nanometers issimultaneously applied to the lateral section of the housing thatsubtends the interface between housing tapered face 88 and lid taperedsurface 158. As represented by plural arrows 219, this photonic energyis applied simultaneously around the whole of the perimeter of the outerhousing. A suitable system capable of performing this welding isavailable from Branson Ultrasonics of Danbury, Conn.

Owing to the transmissivity of the material forming the housing 60 tothis wavelength of photonic energy, the energy passes substantiallythrough the housing lip 84 as represented by phantom arrow 220 of FIG.17. This energy is absorbed by the material forming lid lip 152. Thematerial forming lid lip 152 thus heats to its melting point. Thisincludes the material forming lid tapered surface 158. Owing to thedownward force imposed on the lid 66, the lid therefore settlesdownwardly into the open space of the housing 60. The settling of lid 66stops by the abutment of the bottom surface of lid base 126 againsthousing reveal 90.

Moreover, thermal energy is transferred from the lid tapered surface 158to the adjacent abutting housing tapered surface 88. As represented toFIG. 19, this causes the material forming the housing tapered face 88 tolikewise melt. Collectively, the material forming the opposed housingtapered face 88 and lid tapered surface 158 form a hermetic weld joint221 around and along the interface of the battery housing 60 and lid 66.

It should be appreciated that, as part of the above process, a smallamount of the material forming the housing tapered face 88 and lidtapered surface 158 spread away from these two surfaces. Some of thismaterial, flash material 239 in FIG. 19, flows into the spaceimmediately inward of housing reveal 90 and the contiguous lid notch166. Other of this material, flash material 222, flows into the spacebetween housing vertical surface 86 and lid lip outer vertical surface164.

III. Charger

The basic structure of the battery charger 42 is now explained byreference to FIGS. 20, 20A and 21. Pockets 52 are formed in a front flatportion of the charger housing 50, (flat portion not identified). Thecharger housing 50 is further formed to have a back section 242 that israised relative to the section in which pockets 52 are formed. A rearwall 244 forms the rear end of section 242 and thus, the rear end of thecharger housing 50. Housing rear wall 244 is formed with a set of lowerand upper ribs 246 and 248, respectively. Both ribs 246 and 248 extendvertically. A web 250, part of housing rear wall 244, separates ribs 246and 248 from each other. Ribs 246 are spaced apart from each other todefine vertical vents 252 therebetween. Ribs 248 are spaced apart fromeach other to define vertical vents 254 therebetween.

Battery charger 42 also has a metallic, plate shaped base 256. In oneversion of the invention, the base 256 is formed from spring steel. Base256 is disposed in the open end of housing 50. The base 256 is shaped tohave numerous openings 258 that extend therethrough. Base 256 is thestructural component internal to the charger to which the majority ofother charger components are attached. Not seen are the structuralcomponents and fasteners that hold housing 50 and base 256 together.

One component attached to base 256 is a heat sink 264. In some versionsof the invention, heat sink 264 is formed from aluminum or othermaterial with good thermal conductivity characteristics. The heat sink264 is shaped to have a planar base 266. A number of fins 268 extendperpendicularly outwardly from the base 266. Fins 268 extend laterallyacross the base 266.

The heat sink 264 is mounted to base 256 by brackets 265. Moreparticularly, the heat sink 264 is mounted to the base 256 so that theheat sink is disposed within the space internal to housing back section242. More particularly the heat sink 264 is positioned so that there isfree space between the outer edges of the fins 268 and housing vents 252and 254.

A set of discharge resistors 272 are mounted to the face of the heatsink base 266 opposite fins 268. As discussed below, during certainprocesses for charging or evaluating a battery 42, it is necessary tofirst fully discharge the stored energy in the battery. This processstep is executed by connecting the battery to a discharge resistor 272.In the illustrated version of the invention, each discharge resistor 272is associated with a separate one of the charger pockets 52. During thedischarging of a battery 40, each battery is tied to the specificdischarge resistor 272 associated with the pocket in which the module 54to which the battery is coupled is seated.

Each discharge resistor 272 generally has a resistance of 15 Ohms orless. In still other versions of the invention, each discharge resistor272 has resistance of 10 Ohms or less. Each discharge resistor 272 isoften encased in its own heat sink, (not illustrated). This resistorheat sink is the resistor component that physically abuts the heat sinkbase 266.

Also attached to the heat sink base 266 is a temperature sensor 274. Itwill be observed there is no fan or other device internal to orotherwise integral with the charger 42 for moving air through thehousing 50 or across the heat sink 264.

From FIG. 1 it is seen that each I/O unit 58 includes an LCD display 278and two LEDs 280 and 282. Each I/O unit 58 of charger 40 of thisinvention further includes two membrane switches 284 and 286.

FIG. 22 is a block diagram of the electric circuit assemblies internalto charger 42. A power supply 288 converts the line current into signalsthat can be used to energize the other components internal to thecharger 42. Power supply 288 also produces a signal that is applied,through a module 54 to the battery 40 to charge cells 44.

The charging current is applied to the battery by a current source 290.In actuality, charger 42 has plural current sources 290; one to applycurrent to a battery through each module 54. This allows differentcharging signals to be applied to simultaneously to separate attachedbatteries. For simplicity, only a single current source 290 isillustrated. Integral to each current source 290 is a resistor 292. Whenthe battery 40 is seated in module 54, resistor 292 establishes aconnection between the battery positive terminal and ground. Eachdischarge resistor 272 is associated with a separate one of the currentsources. Thus, in FIG. 22, the discharge resistor 272 is shown internalto the current source 290. Each discharge resistor 272 has one endselectively connected to ground. The opposed end of resistor 272 isselectively tied to the battery positive terminal by a switch, typicallya FET (switch not shown).

Module 54, one shown as a block element in FIG. 18, also includes aresistor 294. Resistor 294 is selectively connected across the terminalsto which battery contacts 70 are connected. A switch, typically a FET(not illustrated) is used to make this connection. Resistor 294 is thusused to measure the voltage at load of the battery 40.

The module 54 also contains a NOVRAM 296. NOVRAM 296 contains chargingsequence and charging parameter data used to regulate the charging ofthe battery 40 charged through the module. A main processor 298, alsointernal to charger 42, controls the charging of the battery 40. Mainprocessor 298 further determines, if it is necessary to perform a stateof health evaluation of a battery, performs the evaluation and, based onthe data generated in the evaluation, generates an indication of thestate of health of the battery. Main processor 298 also generates theread/write instructions to obtain data from and load data into thememory integral with battery microcontroller 46 and module NOVRAM 296.In one version of the invention, the AT91SAM7X256/128 available fromAtmel of San Jose, Calif. functions as the main processor 298.

More specifically, the main processor 298 is connected to the currentsource 290 over a plurality of conductors collectively represented asbus 304. Main processor 298 outputs a variable CURRENT_CONTROL signal tothe current source 290. In response to the CURRENT_CONTROL signal,current source 290 outputs a charging current, at a select current,through module 54 to the battery cells 44. The voltage across resistor292 is output over bus 304 to the main processor 298 as aMEASURED_VOLTAGE signal. This MEASURED_VOLTAGE signal is representativeof the voltage across the battery 40. Also output from the mainprocessor 298 through bus 304 is the signal to the switch thatselectively ties resistor 272 to the battery 40. This connection causesthe charge stored in the battery 40 to be discharge by the resistor 272.

Main processor 298 is connected to the module 54 by a plurality ofconductors represented as a single-wire bus 260. Main processor 298selectively generates the control signal that connects resistor 294across the positive and negative terminals of the battery 40. Whenresistor 294 is so connected, the resistor 294 is connected to resistor292. The MEASURED_VOLTAGE signal from the current source 290 thusbecomes a measure of the voltage at load of the battery 40.

Bus 260 also functions as the link through which the contents of themodule NOVRAM 296 are written to main processor 298. Data are also readfrom and written to the battery microcontroller 46 over bus 260.

The output signal produced by temperature sensor 274 is applied to themain processor 298.

Main processor 298 is also connected to a data transceiver head 301.Transceiver head 301 is the interface internal to the charger connectedto bus 586 (FIG. 26).

A more detailed description of the components internal to module 54 andcurrent source 290 as well as the processes by which a battery may becharged is disclosed in the incorporated by reference U.S. Pat. No.6,018,227. Additional description of the processes involved in chargingplural batteries and alternative charge assemblies are found in theApplicants' Assignee's U.S. Pat. No. 6,184,655, Battery Charging SystemWith Internal Power Manager, issued 6 Feb. 2001, the contents of whichis incorporated herein by reference.

Battery charger 42 also contains an I/O processor 299. The I/O processor299, based on signals output from the main processor 298, generates thesignals that cause LCD display 278 to generate the appropriate image.The I/O processor 60 also regulates actuation of the LEDs 280 and 282.Membrane switches 284 and 286 are also connected to the I/O processor299. Based on the signal generated as a consequence of the opening andclosing of switches 284 and 286, the I/O processor 299 generates theappropriate commands to the main processor 298.

IV. Operation

A. Battery

Battery microcontroller 46 operates in three different modes. This is tominimize the load the components internal to the battery 40 place oncells 44. In a normal mode, all subcircuits internal to themicrocontroller 46 are energized. In one version of the invention, whenmicrocontroller 46 is in this state, it draws approximately 6 mA.Microcontroller 46 also has a power down, clock on state. When themicrocontroller 46 is in this state, CPU 185, analog comparator 191 andthe analog to digital circuit 192 are deactivated. Both the CPU clock189 and the real time clock 190 are on when microcontroller 46 is in thepower down, clock on state. When microcontroller 46 is in the powerdown, clock on state, the microcontroller draws approximately 3 mA.

A power down, clock off state is the lowest power consuming state inwhich microcontroller 46 operates. In this state, the CPU 185, the CPUclock 189, the real time clock 190 and the analog to digital circuit 192are deactivated. When microcontroller 46 is in this state, the analogcomparator 191 is activated. When microcontroller 46 is in the powerdown, clock off state, it draws approximately 120 to 150 μA.

It should further be appreciated that during the states in which theanalog comparator 191 is on, switches internal to microcontroller 46 areset so there is current flow through resistors 209 and 210 to ground.This results in a V_(TEMP) _(—) _(REF) signal appearing at the invertinginput of the comparator. When the analog comparator 191 is turned off,when battery microcontroller 46 is in the power down, clock on state,the microcontroller switches are set so both resistors 209 and 210 aretied high. This eliminates current draw of these resistors.

The operation of microcontroller 46 is now explained by reference to theflow chart of FIGS. 23A and 23B. For the majority of the time, batterymicrocontroller 46 is in the power down, clock off state. In FIG. 21Athis is represented by step 390, the microcontroller entering the powerdown, clock off state. When microcontroller 46 is in this state, analogcomparator 191 continually compares the V_(TEMP) to V_(TEMP) _(—)_(REF), step 392. As long as this comparison indicates that signal fromtemperature sensor 48 indicates that the battery is not beingautoclaved, microcontroller 46 remains in the power down, clock offstate.

It should be appreciated that the reference signal V_(TEMP) _(—) _(REF)may not be a signal that corresponds to the actual temperature insidethe autoclave. Instead to compensate for the thermal insulation of thebattery housing 60 and lid 66, the V_(TEMP) _(—) _(REF) may be at alevel that corresponds to a temperature less than that of the actualautoclave temperature. In some versions of the invention, the V_(TEMP)_(—) _(REF) signal is set to level to be representative of an autoclavetemperature, generally this is an ambient temperature, of at least 100°C. Often, this is an ambient temperature of between 100 and 150° C. Inalternative versions of the invention, it may be desirable to set theV_(TEMP) _(—) _(REF) signal so that the battery is considered in a harshenvironment when in environment when the ambient temperature is at least70° C. The actual level of the V_(TEMP) _(—) _(REF) signal may bedetermined by thermal modeling and/or empirical analysis.

If, in step 392, the comparison indicates that V_(TEMP) is aboveV_(TEMP) _(—) _(REF r) microcontroller 46 interprets V_(TEMP) signal asindicating that the battery is being subjected to autoclaving. Inresponse to this event, microcontroller 46, in step 394, enters thepower down, clock on mode.

As a result of the microcontroller 46 entering the power down, clock onmode, the real time clock 190 counts down a 30 second time period, step396. At the conclusion of this count, the microcontroller 46 transitionsto the normal mode, step 398. Once in the normal mode, in a step 402,using comparator 191 again compares V_(TEMP) to V_(TEMP) _(—) _(REF).

If the comparison of step 402 indicates that the battery is still beingautoclaved, CPU 185 performs a data update step 404. In step 404, datastored in RAM 188 are updated. These data include a field that indicatesthe total time the battery has been at autoclave temperature. In someversions of this invention, the data in this field is simply incrementedby a unit count (one unit=30 sec.). Also data in a RAM field thatindicates the highest temperature of the current autoclave cycle may beupdated. In this part of step 402, a digital signal representative ofthe V_(TEMP) from the analog digital converter 192 are compared to thestored temperature level in the RAM 188. If the data from converter 192is representative of a higher temperature than the stored measurement,these data are overwritten into the RAM field.

Once step 404 is executed, microcontroller 46 reenters the power down,clock on mode. Thus steps 394, 396 and 402 are reexecuted.

Upon completion of the autoclave process, battery temperature will dropto below the autoclave temperature. This event will be indicated by adifferent result in the comparison of step 402. Battery microcontroller46 then updates the data stored in memory 187. This process includes anupdating of the basic history data stored in memory 187, step 408. Aspart of step 408, then count of the number of times the battery has beenautoclaved, the data in field 199 is incremented by one. Based on thedata in the RAM 188 indicating the total time the battery wasautoclaved, the data in the cumulative autoclave time field 200 islikewise revised. Also in step 408, the data in field 204 is updated toindicate the time the battery was, in this last autoclaving, autoclaved.

In step 408, the data in memory 187 are updated based on the RAM dataindicating the total time the battery was, in this autoclavingautoclaved. Specifically, data indicating the total time the battery wasautoclaved in this cycle are written into field 205. The data in field206 indicating the peak single autoclave time is, if necessary, likewiserewritten. In some versions of the invention these data are firstwritten into the RAM.

In a step 410 microcontroller CPU 185 determines if the battery wassubjected to a potentially excessive autoclaving. This step is performedby comparing from RAM 188 the time the battery was autoclaved to aboundary time. This boundary time is the limit of the acceptable timefor which the battery can be autoclaved and there will not be anypotential of damage to its internal components. In some versions of theinvention, this boundary time is between 3 and 60 minutes. In still morepreferred versions of the invention, this boundary time is between 5 and30 minutes.

If the battery was not subjected to a potentially excessive autoclaving,microcontroller returns to the power down, clock off mode. Step 390 isreexecuted.

However, if the comparison of step 410 indicates that the battery mayhave been subjected to a potentially excessive autoclaving, there arefurther revisions to the data in a step 412. In step 412 the data infield 201 indicating the number of potentially excessive autoclaving towhich the battery was subjected is incremented. In some versions of thisinvention these data are first written into the RAM 188. Then, in asingle write-to-flash step, (not illustrated,) all the data written tothe RAM 188 in steps 408 and 412 are written to the flash memory 187.

Also in step 412, the cumulative time to which the battery has beenexposed to potentially excessive autoclaving is updated. This time countis first adjusted by subtracting from the total time of the battery wasautoclaved the boundary time. Thus, if the battery was autoclaved for 12minutes and the boundary time was 10 minutes, by subtraction the CPU 185determines that for this autoclave cycle the battery was subjected to 2minutes of potentially excessive autoclaving. This is the value added tothe cumulative data stored in field 202. Step 390 is then executed toreturn battery microcontroller 46 to the power down, clock off state.

B. Charger

The process by which the charger 42 charges the battery is now 40 is nowdescribed by reference to the flow charts of FIGS. 24A, 24B and 24C.While not illustrated, it should be understood that the depicted processassumes the module 54 is seated in a charger pocket 52. Upon the seatingof each module 54 in a pocket 52, the data in the module NOVRAM 296 areread to the charger main processor 298, (step not shown). In a step 452,main processor 298 continually tests to determine if a battery 42 isseated in a module 54. This test is performed by monitoring the level ofthe current source MEASURED_VOLTAGE signal. Specifically, if a batteryis not seated in a module 54, the MEASURED_VOLTAGE signal is the opencircuit voltage of the charging signal output by the current source. Insome embodiments of the invention, this voltage is 20 VDC. As long asthe MEASURED_VOLTAGE signal remains at the open circuit voltage level,main processor 298 continually reexecutes step 452.

The seating of a battery 40 in the module 54 causes the MEASURED_VOLTAGEsignal to drop. In response to the drop in this signal level, (theseating of the battery in the module,) in a step 453 main processor 298causes battery microcontroller 46 to transition from the power down,clock off mode to the normal mode. In one version of this invention,this transition is effected by tying battery contact 70 to ground for agiven time period. This pulls the one-wire communication line connectedto microcontroller 46 to ground. An interrupt circuit internal tobattery microcontroller 46 (circuit not illustrated) continuallymonitors this communication line. The interrupt circuit interprets theextended low state signal on the communication line as indication thatit should transition the microcontroller 46 from the power on clock offstate to the normal state.

Once the battery microcontroller 46 is in the normal mode, mainprocessor 298 generates an instruction through the module 54 to causethe battery microcontroller 46 to write out to the main processor 298the contents of the associated memory 187. These data are written out tothe main processor 298. The data written to the charger processor 298include the charging sequence instructions and the data describing theuse and autoclave history of the battery. Collectively, this readrequest and data write out are shown as step 456.

Main processor 298 then determines if the data retrieved from memory 187indicates the battery should be subjected to a full state of health(S_O_H) evaluation. One test made to determine if the battery 40 shouldbe so evaluated is, in step 458, the determination based on the dataretrieved from memory file 204. The last entry in file 204 indicates thetotal time the battery was autoclaved in the last autoclaving. Mainprocessor 298, in step 458 compares this value to the boundary time. Ifthe last autoclaving was for a time more than the boundary time, themain processor 298 considers the battery to be in a state in which it isappropriate to perform a state of health evaluation.

As represented by step 460 other data read from the battery memory 187are also tested to determine if a state of health evaluation isrequired. For example, in step 460 the data in the fields 196 and 199are read to determine if, respectively, the battery has been subjectedto more than P number of rechargings or Q number of autoclavings. Alsoin step 460 the data in field 202 are read to determine if, sincemanufacture, the battery has been subject to R amount of total time ofpotential excessive autoclave exposure. It should be appreciated that,in step 460, processor 298 determines it is necessary to perform acomplete state of health evaluation if the battery has been subjected toa multiple of P rechargings, Q autoclavings or R total time ofpotentially excessive autoclave exposure.

Also once the charger processor 298 detects the battery is placed in themodule socket 56, the processor may cause a message to be presented onthe complementary display 278 asking if a state of health evaluation iswanted, (step not shown). The person responsible for charging thebattery 40 indicates if the evaluation is required by depressing anappropriate one of the membrane switches 284 or 286, step 462.

If a state of health evaluation is not required, the charger executes astandard charging sequence for the battery, step 464. In step 464, basedon the sequence instructions received from the battery microcontrollermemory 187 or module NOVRAM 296, charger main processor 298 causes theconnected current source 290 to apply the appropriate sequence ofcharging currents to the battery cells 64. It should be appreciated thatthe charging currents are also based on the MEASURED_VOLTAGE signalsobtained from the current source 290.

Once the charging process is complete, charger 42 performs a voltage atload test on the battery, step 466. Typically, the voltage at load testis performed by measuring the voltage at load across the battery 40.Charger main processor 298 performs this evaluation by asserting theappropriate gate signal to FET integral with the module to whichresistor 294 is attached (FET not illustrated). This results in theconnecting of the module resistor 294 across the positive and negativeterminals of the battery. As a result of resistor 294 being so connectedto the battery, the MEASURED_VOLTAGE signal from the current source 290becomes a measure of the voltage-at-load of the battery. Execution ofthis single test of battery state can be considered the performance of apartial state-of-health evaluation of the battery 42.

In a step 468, main processor 298, through I/O processor 299, causes animage to be presented on display 278 indicating the voltage at load ofthe battery. This data is sometimes referred to as an indication of thebasic state of health of the battery. If the battery voltage at load(basic state of health) is at or above an acceptable level, mainprocessor 298, again through the I/O processor 299, causes anappropriate one of the LEDs 280 or 282 to illuminate to indicate thebattery is available for use, also part of step 468.

In a step 470, main processor 298 writes into battery memory 187 dataregarding the charging. Specifically, in step 470 the count of thenumber of chargings stored in memory field 196 is incremented. Also dataare added to file 197 to indicate the measured voltage-at-load of thebattery after charging.

Eventually, the battery 40 is removed from the charger 42, step 471. Asa consequence of this step, there is no communication over the one-wireline internal to the battery 40. The signal on this line transitions toa continuous high level state. As discussed above with respect to step453, the signal level on this communications line is monitored by aninterrupt circuit. The interrupt circuit interrupts the signal level ofthe communications line being high for an extended period of time as anindication that step 471 was executed. Therefore, in step 472, theinterrupt circuit transitions the battery microcontroller from thenormal state back to the power down, clock off state. Charger 42 returnsto step 452.

While not shown, it should be understood that after the charging processis completed, main processor 298 also causes one of the LEDs to beappropriately actuated to indicate that the battery is available foruse.

As represented by step 478, a battery full state of health evaluationstarts with the complete discharging of the battery. Step 478 isexecuted by the main processor 298 asserting the appropriate gate signalto tie the battery positive terminal to resistor 272. Periodically, thevoltage across the battery is measured, step 480. This step is executeduntil it is determined the battery is fully discharged.

Once the battery 40 is fully discharged, charger 42 proceeds to chargethe battery, step 484. Step 484 is essentially identical to step 464. Aspart of this evaluation, main processor 298, in step 484, also monitorsthe overall length of time it takes for the cells 64 internal to batteryto fully charge. As is known in the art, main processor typicallydetermines the cells are full charged by determining when change involtage over a period time falls to a value less than 0, (negativeslope.) Thus, in step 486 during the primary or main state charging ofthe battery 40, main processor 298 monitors both theΔV_(BATTERY)/Δ_(Time) and the time from the start of the main statecharging it takes for this slope to go negative. This time is T_(FULL)_(—) _(CHARGE).

Once the main state charging of the battery is complete, charger 42performs a voltage at load test, step 488. Step 488 is essentiallyidentical to the voltage at load test of step 466.

Based on the data obtain in steps 486 and 488, main processor 298determines if the health of the battery is such that it can supply theamount of power needed to actuate a powered surgical tool. In a step490, main processor 298 makes this determination by determining if theoverall time it took the battery to fully charge, T_(FULL) _(—)_(CHARGE), is at or above a threshold time, T_(THRESHOLD). The basis forthis evaluation is that the T_(FULL) _(—) _(CHARGE) time is directlyproportional to the quantity of charge being stored in the battery.Therefore, if T_(FULL) _(—) _(CHARGE)>T_(THRESHOLD), this is anindication that the quantity of charge in the battery is above thatneeded to energize a surgical tool for the total time such power isrequired. Thus, when the above determination tests true, main processor298 recognizes the battery as being in state in which it most likely canpower the surgical instrument as required.

If the determination of step 490 tests false, main processor 298considers the battery to be in the opposite state. In this event, mainprocessor 298 causes the I/O processor 299 to generate the appropriatefault state message, step 492, regarding the battery 40 on the display278. This provides notice the battery may not function appropriately.

As part of the state of health evaluation, main processor 298 determineswhether or not the voltage at load is above a minimum voltage value,step 494. If the battery voltage at load is not above this minimumvalue, the battery is considered to have an internal resistance so highthat it cannot appropriately energize the tool to which it is attached.Therefore, if in a step 494 the determination tests false, step 492 isexecuted.

As part of the state of health evaluation, main processor 298 furtherdetermines whether or not the battery can deliver sufficient chargebased on both T_(FULL) _(—) _(CHARGE) and the measured voltage at load.Specifically, both T_(FULL) _(—) _(CHARGE) and measured voltage at loadvalues are normalized, step 496. In some version of the invention, eachof these values is normalized by quantifying them to a range forexample, between 0.0 and 1.0.

Then, in a step 498 the normalized T_(FULLCHARGE) and V_(ATLOAD) valuesare used as input variables into an equation. This equation may be asimple summation,

S _(—) H _(—) R=T _(FULLCHARGE) +V _(ATLOAD)  (1)

Here S_H_R is state of health result. Alternatively, the normalizedvalues are multiplied by coefficients

S _(—) H _(—) R=A(T _(FULLCHARGE))+B(V _(ATLOAD))  (1a)

Here, A and B are constants. In some versions of the invention, thevariables are multiplied together:

S _(—) H _(—) R=C(T _(FULLCHARGE))(V _(ATLOAD))+D  (1b)

Here, C and D are constants.

Once S_H_R is calculated, in step 502, it is compared to a cutoff value,S_H_R_(CUTOFF). If S_H_R is equal to or greater than S_H_R_(CUTOFF), thecharger main processor 298 recognizes the battery as being in a state inwhich it will deliver an appropriate charge to a surgical tool.Therefore, a step 504 is executed to cause the appropriate image to bepresented on the display 282 and LED activation to indicate the batteryis available for use. Also in step 504 the charger presents on display278 an indication of the above calculated S_H_R result. These data arereferred to as an indication of the calibrated state of health of thebattery. If, in step 502 it is determined that the calculated S_H_Rvalue is less than S_H_R_(CUTOFF), step 492 is executed.

After either step 492 or 504 is executed, step 470 is executed tocomplete the charging process. (Not shown is the loop back to step 470.)

Charger 42 of this invention is further configured so that whenactuated, temperature sensor 274 provides a signal to main processor 298representative temperature of the heat sink 264. As represented by step508 of FIG. 25, main processor 298 monitors the heat sink temperature,T_(H) _(—) _(S). As represented by step 510, the main processor comparesthe heat sink temperature to a limit temperature, T_(H) _(—) _(S) _(—)_(LMT).

When charger 42 of this invention is required as part of a chargingprocess or a state of health evaluation to discharge a battery 40, thebattery charge is discharged through one of the resistors 272. The heatgenerated by this resistor is conductively transferred to heat sink 272.Most of the time air flow into the charger housing through base openings258 and housing vents 252 has sufficient thermal capacity to sink theheat radiated by heat sink 272. This warmed air is discharged throughhousing vents 254. During such time periods the heat sink temperaturesstays below the heat sink limit temperature.

However, there may be times the air flow past the heat sink 264 cannotsink all the heat sourced by the heat sink 264. This may occur if, dueto unusual circumstances, the charger simultaneously discharges largeamounts of current from plural batteries. If this event occurs, themeasured rises heat sink temperature rises. If the heat sink temperaturerises above the limit temperature, T_(H) _(—) _(S) _(—) _(LMT), there isa possibility that further temperature rise will result in the chargerhousing 52 being heated to a temperature that makes it unpleasant, orworse, to touch the charger 42. The limit temperature, T_(H) _(—) _(S)_(—) _(LMT), it should be appreciated, is often determined by empiricalanalysis.

Therefore, if the comparison of step 510 indicates the heat sinktemperature is above the limit temperature, main processor 298 executesa battery discharge interrupt sequence represented by step 510. In thissequence, the charger interrupts the discharging of one or more attachedbatteries 40. Thus, in step 510, the discharge step 478 to which one ormore of the batteries is presently being subjected may be interrupted.Similarly, if one of the batteries is being discharged as part of thenormally charging sequence for that battery, that discharge step maylikewise be interrupted.

Step 510 is executed until, as a result of a subsequent measurement ofheat sink temperature, (step not shown) it is determined heat sinktemperature has dropped below a restart temperature, T_(H) _(—) _(S)_(—) _(RSTRT), step 512. Once the heat sink temperature is fallen tothis level, additional thermal energy sourced by the dischargedresistors 272 can be output without the likelihood of such heat placingthe charger in an undesirable state. Therefore, once the heat sinktemperature so drops, step 510 is terminated.

Battery 40 of this invention provides an indication if its cells mayhave been damaged. If the battery 40 may be in this state, charger 42conducts a state of health evaluation on the battery. One immediateadvantage of this invention is that, if the battery cells may have beendamaged, a state of health evaluation is performed. This substantiallyreduces the possibility that someone will attempt to use a damagedbattery to energize a surgical tool.

During the charging or discharging of the battery 40, the temperature ofcells 44 inevitably rises. In this invention, each cell has some surfacearea that is spaced free of the adjacent cells. This minimizes theuneven heat dissipation and consequential uneven temperature rises ofthe cells. The reduction of this temperature imbalance results in a likelessening of the extent to which the individual cells 44 can becomeelectrically imbalanced. Reducing the electrical imbalance of the cellsreduces the extent to which the cells being so imbalanced can adverselyaffect either the utility or useful lifetime of the battery.

Battery 40 of this invention is also designed so that the narrow section119 of fuse 118 is spaced from the adjacent binders 108 and 110. Section119 is the section of the fuse 118 that vaporizes upon the flow of morethan the selected amount of current flow through the fuse. Since fusesection 119 is not in physical contact with another section of thebattery, no other section of the battery, such as the binders, serve assinks for the heat generated by the current flow. Thus when the definedcurrent flows through the fuse 118 the thermal energy generates in thevicinity of fuse section 119 stays in the section. This thermal energytherefore causes the fuse section 119 to rise to the level at whichvaporization occurs. Thus, this design feature of the battery of thisinvention increases the likelihood that, when more than the definedcurrent flows through the fuse, the fuse will open.

The charger 42 is further configured that it does not always perform thestate of health evaluation, which can be time consuming to perform.Instead, the charger of this invention only performs this evaluationwhen the environmental history stored in the battery indicates it isdesirable to perform the evaluation. By minimizing the number of timesthe charger performs state of health evaluations, the time it takes thecharger to charge batteries is likewise held to a reasonable timeperiod.

Still another feature of charger 42 is that the charger dischargesbatteries as part of a charging sequence or state of health evaluationyet it does not include a fan or other powered ventilation unit toexhaust air heated as a consequence of this discharging. The absence offan in this charger reduces the noise generated by the charger when itis active. In the event there is an excessive generation of heat,further battery discharging is limited until the heat is dissipated.

Also battery 40 invention stores data regarding the environment to whichthe battery has been exposed. This information can be used to helpevaluate why a battery underperforms and further provide feedback withregard to the charging and sterilization processes to which the batteryis subjected.

Further, the laser welding assembly of the battery lid 60 to theunderlying housing 66 eliminates the need to use fasteners to accomplishthis attachment. Weld joint 221 formed by this process likewiseeliminates the need to provide a separate seal to form an air-tighthermetic barrier between these components.

C. Tool Communication

As depicted by FIG. 26, in a system 520 of this invention, battery 40 isused to energize a cordless powered surgical tool 522. The depicted tool522 is a surgical sagittal saw. It should, of course, be recognized thatthe system of this invention is not limited to this type of tool or onlytools with motors. FIG. 27 is a block diagram of components of tool 522relevant to system 520 of this invention. Tool 522 has a power generator524. The power generator 524 is the component internal tool 522 thatactuates a surgical attachment 526. In the depicted invention, the powergenerator 524 is a motor; surgical accessory 526 is a saw blade. Acoupling assembly 528 removably holds the surgical attachment to thetool 522. Integral with the attachment is identification component 530,such as an RFID. An attachment reader 532, part of tool 522 reads thedata stored by the identification component 530.

A power regulator 534 selectively applies the energy output by battery40 to the power generator 524. The power regulator 534 applies power tothe power generator 524 based on instructions received from a controlprocessor 536. Control processor 536 generates instructions to the powerregulator 534 in part based on the depression of control membersintegral with the tool; (control members not illustrated). Controlprocessor 536 receives from the attachment reader 532 the data read fromthe attachment identification on component 530.

Also internal the tool 522 is one or more sensors that monitor theoperation of the tool. For simplicity only a single sensor a temperaturesensor 538, is illustrated. When tool 522 includes a motor as the powergenerating unit, temperature sensor 538 is often placed in closeproximity to a bearing assembly integral with the motor. The outputsignal generated by temperature sensor 538 is applied to tool controlprocessor 536.

Tool 522 also has a data transceiver head 535. Head 535, which may beimplemented in hardware or software, is designed to communicate withbattery microcontroller 46. In one version of the invention, datatransceiver head 535 consists of a software executed by tool controller536 to exchange signals with battery microcontroller 46 and a contactintegral with the tool 522 designed to establish a conductive connectionwith battery contact 72.

A more detailed description of the structure of a tool 522 integral withsystem 520 of this invention is found in the Applicants' Assignee'spreviously referenced U.S. Patent Application No. 60/694,592, POWEREDSURGICAL TOOL WITH SEALED CONTROL MODULE, the contents of which areincorporated herein by reference.

During the use of tool 522 and battery 40 of this invention, dataregarding the use of the tool are stored in the battery memory 187. Moreparticularly, these data are stored in memory tool history file 229.FIG. 23 depicts in more detail types of data stored in the tool historyfile 229. A first file internal to file 229 is a tool identificationfile 542. File 542 contains data that identifies the tool 522 to whichthe battery 40 is attached.

Data regarding the total time the tool is run is contained in an overallrun time odometer field 544. Data indicating the times the powergenerator 524 is run above or below specific operating state(s) isstored in one or more operating mode run time odometer fields 546. Forexample, if the tool power generator 524 is a motor, a first field 546may store data indicating the overall time the motor is run at aparticular speed. A second field 546 is used to store data indicatingthe overall time the motor is run under load. Tool control processor 536makes a determination of whether or not the motor is run under loadbased on the current drawn by the motor. If the tool power generator 524is a part of an ablation tool, an operating mode run time powergenerator field 546 stores data indicating the total time the tool isused to heat tissue to a particular temperature.

Tool history file 229 also contains a sensor output log file 548. File548 is used to store data based on the signals generated by the sensorassociated with the tool. In some versions of the invention, the datastored in file 548 are signals representative of the actual parametersensed by the sensor. For example, if one sensor is a temperaturesensor, the data in file 548 can include data indicating the peaktemperature detected by the sensor. Alternatively, file 548 includesflags that are set as a function of the tool or environmental statessensed by the sensor. Thus, system 520 of this invention is set so thatif the sensor 538 detects a temperature above a threshold level, a flagindicating that the tool reached such a temperature is set.

Also internal to tool history file 229 is an attachment log file 550.Accessory log file 550 contains data that identifies the specificattachment(s) 526 attached to the tool 520. These data are based on thedata collected by the tool attachment reader 532. In some versions ofthe invention, each attachment file contains for each attachment, totalrun time odometer data, operating mode run time data and data based onthe output from the sensors during use of the attachment.

A process by which data are loaded into and retrieved from the batterymicrocontroller memory 187 are now described by reference to FIG. 29.Step 560 is the coupling of the battery to the tool. As a result of thisstep, there is immediate current flow to the tool and the subsequentactuation of the tool control processor 536, step 562. As part of theinitial actuation sequence, tool control processor 536 pulls theone-wire communication line internal to the battery low so as to causebattery microcontroller 46 to transition from the power down, clock offstate to the normal state, step 564. Tool control processor 536, in astep 566, then writes into battery microcontroller memory file 187 dataidentifying the tool.

Step 568 represents the actuation of the tool. At this time, toolcontrol processor 536 engages in an initial collection of data regardingthe operation of the tool, step 570. Step 570 involves determining fromthe attachment reader 532 the identity of the specific attachment 526coupled to the tool. The data obtained in step 570, as part of the step,are stored in a RAM associated with the tool control processor 536 (RAMnot shown).

As long as the tool continues to be actuated, tool control processor536, in a step 572 acquires and stores data regarding the toolactuation. These data, for example, include total run time odometer dataand data indicating run time in one or more states, for example, speedlevel, running at load or operating at a particular temperature. Thesedata are likewise stored in the microcontroller RAM.

In a step 574 the tool is deactuated. In an immediate next step 576,tool control processor 536, through data transceiver head 535, updatesthe data log of the use of the tool in the battery microcontrollermemory tool file 229. Thus, after each individual actuation of the tool,the data recorded in the odometer logs fields 544 and 546 are updated.It should be appreciated that not all of the data may be updated. Forexample, if peak temperature is measured during the first actuation ofthe tool, the temperatures reached in any subsequent actuations are notrecorded.

Once use of the tool 522 is completed, battery 40 is disconnected, step578. This results in battery one-wire communication line going high.This transition is detected by the interrupt circuit internal to themicrocontroller 46. This signal staying high for an extended period oftime is interpreted by the microcontroller as indicating the battery hasbeen disconnected from the tool 522. Therefore, in a step 580, themicrocontroller returns the battery to the low power consuming, powerdown, clock off state.

As discussed above with respect to FIG. 24A, once the battery isattached to the charger, in step 456, the data in the batterymicrocontroller memory 187 are written out to the charger main processor298. As part of this process, the data in the tool history file are readout, step 582 of FIG. 29.

Returning to FIG. 26, it can be seen that the charger 42 is connected bya bus 586 to other components at the medical facility at which system520 is installed. This connection is through charger transceiver head301. The transceiver head 301 is the sub-circuit internal to the chargerthat allows charger processor 298 to exchange data and instructions withother components connected to bus 586.

The additional components connected to bus 586 include, for example, apersonal computer 588. Thus in a step 590, the charger main processor298 forwards the data in the battery memory tool history field 229 toanother component on the attached network, for example the personalcomputer 588. Bus 586 may even have a telecommunication head (notidentified). The telecommunications exchanges signal passed over the buswith signals on an external network such as a PSTN or external network.

This arrangement provides a log of the use of the cordless surgical tool522 of the system 520 available to persons charged with maintaining thetool. For example, the data in the tool history file may indicate thetool reached a particular operating temperature. The occurrence of thisevent is recognized as indication the tool may require maintenance. Inthis event, a message regarding tool state may be transferred by theexternal network to an off site repair facility. Upon receipt of thisnotice, the repair facility can schedule the repair or replacement ofthe tool prior to the tool becoming inoperable. The data retrieved fromtool history file 229 may likewise be used to provide information forwarranty purposes or to ensure that, if the tool is approaching the endof useful life time, the relevant individuals receive notice of thisfact.

V. Alternative Embodiments

It should be appreciated that the foregoing description is directed toone specific version of the battery and related components of the systemof this invention. Other versions of this invention may have alternativefeatures, constructions and methods of execution.

Thus, there is no requirement that each of the above inventive featuresbe found in all embodiments of the invention.

For example, in some versions of the invention, the battery may not besealed from the ambient environment. In these and other versions of theinvention, the sensor internal to the battery may be one that is used todetermine the exposure to an environmental agent other than temperaturethat could adversely affect charge storage by the cells 44. Thus, thesensor internal to the battery could detect humidity. If the sensordetects that the atmosphere within the battery is of relatively highhumidity, data logging this event are stored in the battery memory.Another alternative sensor is an accelerometer. Such a device wouldrecord a rapid deceleration of the battery if it was dropped. Again,such an event would be logged in the battery memory. Then if the charger42, upon reading the stored data, recognizes that the battery wasexposed to the unusual environment event, the charger would subject thebatter to the complete state-of-health evaluation.

Alternatively, an accelerometer or other sensor may be employed to sensewhether or not the battery is excessively vibrated. Data regarding theexcessive vibration is likewise stored in the battery memory.

With regard to the above it should also be understood that occurrence ofone of the above environmental events may be the trigger that causes thebattery to transition from the power down mode to the normal mode.

Further it should be appreciated plural such environmental sensor may befitted to the battery.

Similarly, alternative constructions that come within the scope of theinvention are also possible. Thus, a battery may be provided with cellshaving less or more than the eight (8) cells illustrated in the versionof the invention illustrated in FIG. 6. For example, to provide abattery with ten (10) cells that has the heat dissipating cellarrangement of this invention, plural middle rows of cells, each havingno more than two (2) cells per row may be provided. Also outer rows ofcells with fewer or more than the three (3) cells may be provideddepending on the number of cells the array is to have. In some versionsof the invention, arrays of cells may be stacked one on top of theother.

Similarly, there is no requirement that in all versions of the inventionthe laser welding be performed using a laser that emits photonic energyat 980 nanometers. For example, in some versions of the invention, thelaser welding may be performed with a laser that emits coherent lightenergy at 808 nanometers. Again, this is just exemplary, not limiting.It should likewise be appreciated that other medical equipment, not justbatteries, may be laser welded using the process of this invention.

In this vein, it is further understood that there is no requirement thatin all versions of the invention, the top of the housing always functionas the component that is seated in the base and heated by the photonicenergy. In other versions of the invention, this relationship may bereversed. Clearly, the laser welding may be used to assemble othercomponents forming the housing together. Thus, the method may be used tosecure multiple panels together.

Likewise, there is no requirement that the geometries along which thecomponents forming the battery housing meet have the disclosed geometry.In some versions of the invention, either neither or only one of thesurfaces along which the weld seam is formed may have a tapered profile.

Similarly, in some versions of the invention, the battery may onlycontain a non-volatile memory. When the battery is attached to the tool,the tool writes data to the memory. Then, when the battery is attachedto the charger the charger reads out the data written into the memory bythe tool so the data can be forward to the appropriate destination.

Clearly, there is no requirement that all versions of the invention beconstructed to energize and communicate with powered surgical tools.Thus, the battery of this invention can be used to energize powerconsuming devices other than surgical tools. The communications systemof this invention can be used to obtain data from devices other thancordless surgical tools.

It should likewise be appreciated that the components and process stepsof this description are only exemplary and not limiting. For example, insome versions of the invention, the multiple components internal to thebattery may function as the memory in which data are stored and thedevice that writes to and reads data from the memory. Likewise, in someversions of the invention, tool control processor 536 may, duringactuation, simultaneously log data into the battery memory.

Circuit variations are also possible. Thus, in some versions of thisinvention, the end of resistor 209 opposite the V_(TEMP) _(—) _(REF)junction may be tied to the output pin of voltage converter 182. Inthese versions of this invention, the end of resistor 210 oppositeV_(TEMP) _(—) _(REF) junction is tied to V_(SS) or the BATT-terminal. Anadvantage of this version of the invention is that it results in aV_(TEMP) _(—) _(REF) signal that does not vary with manufacturingdifferences in microcontroller 46.

There is no requirement that all chargers of this invention be able tosimultaneously charge plural batteries. There is no requirement acharger accept different modules so the charger is able to chargerdifferent types of batteries.

Also, it should be recognized that the power generator 524 need notalways be a motor. The power generator may be a device that generateselectrical energy, RF energy, ultrasonic energy, thermal energy orphotonic energy.

Returning to FIG. 12, it can be seen that the battery may also beprovided with a wireless transceiver 602. This transceiver may be an RFor IR unit. In some versions of the invention, the transceiver may be aBluetooth transceiver. When the battery is connected to the tool,transceiver 602 exchanges signals with a complementary transceiver 604attached to bus 586. Thus, this version of the invention allows realtime communication between the cordless tool 522 and other operatingroom equipment through battery 40. For example using this arrangement, avoice actuated control head 606 can be used to regulate tool actuation.Thus, a command entered through control head 606 is packetized and sentover bus 586 to transceiver 604. Transceiver 604 broadcasts the commandto battery transceiver 602. The command is transferred from the batterytransceiver to the battery microcontroller 46. Microcontroller 46, inturn, forwards the command through the tool transceiver head 535 to thetool processor 530. Tool processor 530, in turn, generates theappropriate commands to the power regulator 534 to cause desiredactuation of the power generator 524.

Similarly, a surgical navigation system 610 may likewise be connected tothe tool through transceivers 602 and 604. The surgical navigationsystem tracks the position of the tool 520 and attachment 526 relativeto the surgical site to which the attachment is applied. If thenavigation system determines that the attachment is being position at alocation at which it should not be used, the attachment would generate astop command. This command is transmitted through transceiver 604 totransceiver 602 and, from transceiver 602, to the tool control processor536. Tool control processor 536, upon receipt of the command, at leasttemporarily deactivates or slows operation of the tool 522.

It should likewise be understood that the not all batteries of thisinvention may be designed to withstand the rigors of sterilization.Alternatively, the features of this invention may be incorporated intoan aseptic battery pack. This type of battery pack includes asterilizable housing that defines a void space for receiving a removablecell cluster. A sealable lid associated with the housing allowsinsertion and removal of the cell cluster. With this battery pack, priorto sterilization, the cell cluster is removed from the housing. Thus thecells of an aseptic battery pack are spared the rigors of autoclavesterilization. The Applicants' Assignee's U.S. patent application Ser.No. 11/341,064, filed 27 Jan. 2006, ASEPTIC BATTERY WITH REMOVABLE CELLCLUSTER, now U.S. Pat. No. 7,705,559 B2, the contents of which areincorporated herein by reference, discloses one such aseptic batterypack. Still, the features of this invention may be built into thehousing and or cell cluster of an aseptic battery pack.

Thus, it is an object of the appended claims to cover all suchvariations and modifications that come within the true spirit and scopeof this invention.

What is claimed is:
 1. A method of assembling a rechargeaable battery,said method including the step of: providing a first housing component,the first housing component formed from a polyphenysulfone plastic thatdoes not appreciably interfere with the transmission of photonic energyat a select wavelength and that is formed to have an outer surface, anedge around the outer surface and an inner face that extends from theedge and is located inwardly from the outer surface; providing a secondhousing component, the second housing component formed from apolyphenysulfone plastic that absorbs photonic energy emitted at theselect wavelength and that is formed to have an outer surface and a lipthat extends outwardly from and is located inwardly of the outer surfaceof the second housing component and wherein the first and second housingcomponents are collectively shaped so that when so that when the housingcomponents are placed together: the lip of the second housing componentabuts the inner face of the first housing component and adjacent wherethe lip and the inner face of the first housing component abut there isa void, the void being located inwardly of the outer surfaces of thehousing components; placing at least one rechargeable cell in one of thehousing components and connecting the cell to terminals mounted to oneof the housing components; placing the housing components together sothe lip of the second housing component abuts the inner face of thefirst housing component; directing photonic energy at the selectwavelength towards the outer surface of the first housing component sothat the photonic energy passes through the first housing component andis absorbed by the lip of the second housing component, so that: thephotonic energy heats the lip so as to cause the melting of the lip andthe transfer of thermal energy to the first housing component so as toform a weld joint along the interface between where the lip of thesecond housing component abuts the inner face of the first housingcomponent; and flash formed by said welding flows into the void betweenthe first and second housing components.
 2. The method of assembling arechargeable battery of claim 1, further including of placing a pressureon the housing components so that, during said welding step, innersurface of the first housing component and the lip of the second housingcomponent are pressed together.
 3. The method of assembling arechargeable battery of claim 2, wherein said step of placing a pressureon the housing components is performed simultaneously with said step ofdirecting photonic energy at the first housing component.
 4. The methodof assembling a rechargeable battery of claim 1, wherein: in said stepof providing the first housing component, the first housing componentthat is provided is further shaped so that the inner face is tapered;and in said step of providing the second housing component, the secondhousing component that is provided is further shaped so that lip has aface surface that has a taper complementary to the taper of the innerface of the first housing component so that, as a result of said step ofplacing the housing together, the tapered face surface of the lip of thesecond housing component abuts the tapered inner surface of the firsthousing component.
 5. The method of assembling a rechargeable battery ofclaim 4, wherein, simultaneously with said step of directing thephotonic energy towards the outer surface of the first housingcomponent, placing a pressure on one of the housing components so thattapered inner surface of the first housing component and the taperedface of the lip of the second housing component are pressed together. 6.The method of assembling a rechargeable battery of claim 1, furtherincluding the step of, prior to said step of placing the housingcomponents together, placing a microcontroller that is powered by andconnected to said at least one rechargeable cell in one of the housingcomponents.
 7. The method of assembling a rechargeable battery of claim1, wherein: in said steps of providing the first housing component andthe second housing component: one of the first or second housingcomponents is provided with a reveal that is spaced from where the weldjoint between the housing components is formed and that is directed toan adjacent surface of the other one of the second or first housingcomponents; the housing components are collectively shaped so that, as aresult of performing said step of placing the housing componentstogether, the housing component on which the reveal is not formed isspaced away from the reveal; and during said formation of the weldjoint, the housing components are urged together and the abutment of thehousing components is stopped by the abutment of the housing componentthat is not formed with the reveal against the reveal.
 8. The method ofassembling a rechargeable battery of claim 1, wherein as a result ofsaid step of directing photonic energy towards the outer surface of thefirst housing component, the weld joint that forms between the housingcomponents is a hermetic weld joint.
 9. The method of assembling arechargeable battery of claim 1, wherein in said step of providing thesecond housing component, the second housing component that is providedcontains a dye, the dye being formed material that absorbs photonicenergy emitted at the select wavelength.
 10. The method of assembling arechargeable battery of claim 1, wherein: in said step of providing thefirst housing component, the first housing component that is providedcontains a dye that is opaque at visible wavelengths and that istransparent at the select wavelength; and in said step of providing thesecond housing component, the second housing component that is providedcontains a dye, the dye being formed material that is opaque at visiblewavelengths and that absorbs photonic energy emitted at the selectwavelength.
 11. The method of assembling a battery of claim 1, whereinin said step of providing the first housing component, the first housingcomponent is formed from a polyphenysulfone plastic that does notappreciably interfere with the transmission of photonic energy having awavelength that is at least one of 808 nanometers or 980 nanometers. 12.A rechargeable battery manufactured according to the steps of: providinga first housing component, the first housing component formed from apolyphenysulfone plastic that does not appreciably interfere with thetransmission of photonic energy at a select wavelength and that isformed to have an outer surface, an edge around the outer surface and aninner face that extends from the edge and is located inwardly from theouter surface; providing a second housing component, the second housingcomponent formed from a polyphenysulfone plastic that absorbs photonicenergy emitted at the select wavelength and that is formed to have anouter surface and a lip that extends outwardly from and is locatedinwardly of the outer surface of the second housing component andwherein the first and second housing components are collectively shapedso that when so that when the housing components are placed together:the lip of the second housing component abuts the inner face of thefirst housing component; placing at least one rechargeable cell in oneof the housing components and connecting the cell to terminal componentsmounted to one of the housing components; placing the housing componentstogether so the lip of the second housing component abuts the inner faceof the first housing component so that the first housing componentsurrounds the lip of the second housing component; directing photonicenergy at the select wavelength towards the outer surface of the firsthousing component so that the photonic energy passes through the firsthousing component and is absorbed by the lip of the second housingcomponent, so that the photonic energy heats the lip so as to cause themelting of the lip and the transfer of the thermal energy to the firsthousing component so as to form a weld joint along the interface betweenwhere the lip of the second housing component abuts the inner face ofthe first housing component so that the weld joint forms a hermetic sealbetween the housing components and the weld joint is located inwardly ofthe outer surfaces of the housing components.
 13. The rechargeablebattery of claim 12, further including the step of placing a pressure onthe housing components so that inner surface of the first housingcomponent and the lip of the second housing component are pressedtogether.
 14. The rechargeable battery of claim 13, wherein in said stepof placing a pressure on the housing components, is performedsimultaneously with said step of directing the photonic energy at thefirst housing component.
 15. The rechargeable battery of claim 12,wherein: in said step of providing the first housing component, thefirst housing component that is provided is further shaped so that theinner face is tapered; and in said step of providing the second housingcomponent, the second housing component that is provided is furthershaped so that lip has a face surface that has a taper complementary tothe taper of the inner face of the first housing component so that, as aresult of said step of placing the housing together, the tapered facesurface of the lip of the second housing component abuts the taperedinner surface of the first housing component.
 16. The rechargeablebattery of claim 15, wherein, simultaneously with said step of directingthe photonic energy towards the outer surface of the first housingcomponent, placing a pressure on one of the housing components so thattapered inner surface of the first housing component and the taperedface of the lip of the second housing component are pressed together.17. The rechargeable battery of claim 12, further including the step of,prior to said step of placing the housing components together placing amicrocontroller that is powered by and connected to said at least onerechargeable cell in one of the housing components.
 18. The rechargeablebattery of claim 12, wherein: in said steps of providing the firsthousing component and the second housing component: one of the first orsecond housing components is provided with a reveal that is spaced fromwhere the weld joint between the housing components is formed and thatis directed to an adjacent surface of the other one of the second orfirst housing components; the housing components are collectively shapedso that, as a result of performing said step of placing the housingcomponents together, the housing component on which the reveal is notformed is spaced away from the reveal; and during said formation of theweld joint, the housing components are urged together and the abutmentof the housing components is stopped by the abutment of the housingcomponent that is not formed with the reveal against the reveal.
 19. Therechargeable battery of claim 12, wherein in said step of providing thesecond housing component, the second housing component that is providedcontains a dye, the dye being formed material that absorbs photonicenergy emitted at the select wavelength.
 20. The rechargeable battery ofclaim 12, wherein in said step of providing the first housing component,the first housing component is formed from a polyphenysulfone plasticthat does not appreciably interfere with the transmission of photonicenergy having a wavelength that is at least one of 808 nanometers or 980nanometers.
 21. The rechargeable battery of claim 12, wherein: in saidstep of providing the first housing component, the first housingcomponent that is provided contains a dye that is opaque at visiblewavelengths and that is transparent at the select wavelength; and insaid step of providing the second housing component, the second housingcomponent that is provided contains a dye, the dye being formed materialthat is opaque at visible wavelengths and that absorbs photonic energyemitted at the select wavelength.
 22. The rechargeable battery of claim12, wherein: in said steps of providing the first and second housingcomponents, first and second housing components are provided that arecollectively shaped so that when so that when the housing components areplaced together: the lip of the second housing component abuts the innerface of the first housing component and adjacent where the lip and theinner face of the first housing component abut there is a void, the voidbeing located inwardly of the outer surfaces of the housing components;and during said step of directing the photonic energy at the firsthousing component flash formed by the formation of the weld joint flowsinto the void between the first and second housing components.